The present invention is concerned with reducing noise caused during operation of fluid control valves. In particular, the invention is concerned with valves of the type comprising a float member displaceable within a housing between closed and opened positions, responsive to fluid level and fluid dynamics within a vessel.
Valves of the referred to type are often fitted in vehicle fuel tanks and the like. Such valves have one or more functions, e.g.: roll-over valve (ROV), over-filling interdiction valve (OFI), filling-limit vent-valve (FLVV) and on-board recovery valve (OBRV), as known in the art. Valves incorporated in vehicles"" fuel tanks are a mere example. It will be appreciated however, that such valves may be fitted in a variety of other vessels wherein fluid control is required.
Such valves typically comprise a housing fitted to the vessel, e.g. a fuel tank, with a float member displaceable within the housing, responsive to fluid level and fluid dynamics within the vessel, between closed and opened positions. Typically, when the float member is displaced into a sealing position there are provided resilient sealing means which dampen the impacting noise of the float member encountering the outlet port of the housing. However, during opening displacement of the float member, typically in a downward direction, the float member encounters a wall of the housing, resulting in an impacting noise.
In some cases there is provided a spring member slightly biasing the float member upwardly towards the closed position. However, the biasing force of this spring is essentially soft and the downward displacement of the float member overcomes the biasing spring.
During filling of a vessel and during moving of the vessel, e.g. fueling and travelling of a vehicle, respectively, the float member constantly displaces within the housing whereby an irritating clicking noise may be heard each time the float member encounters the housing.
By some proposed standards, within several years, fuel control valves within vehicle""s fuel tanks will have to be provided with means for reducing that impacting noise.
It is thus an object of the present invention to provide a valve fitted with an arrangement for reducing the impacting noise between the housing and the valve member displaceable therewithin.
It is an object of the invention to provide a silenced fuel control valve wherein displacement of the float element within the valve and its impacting against walls of the housing is essentially silent.
In accordance with the present invention there is provided a valve for a fluid tank, the valve comprising a housing formed with one or more inlet and outlet ports, side walls and a seating wall portion supporting a float-type valve member; the valve member being axially displaceable within the housing responsive to fluid level within the tank, between an uppermost position and a lowermost position; the valve member has a top and a bottom end and a bearing portion bearing facing the seating wall portion of the housing;
the valve characterized in that either one or both of the seating wall portion of the housing and the bearing portion of the valve member, are fitted with at least one dampening member for diminishing impacting noise of the valve member encountering the housing upon displacement into the lowermost position.
In accordance with one aspect of the invention the seating wall portion of the housing is a bottom wall thereof, and the bearing portion of the valve member is a corresponding, facing bottom wall thereof.
In accordance with one specific design, the seating wall portion of the housing is a laterally extending shoulder formed adjacent a top end of the housing, and where the bearing portion of the valve member is a corresponding laterally projecting wall portion adjacent the top end thereof. By one embodiment of this design, the lateral shoulder of the housing is formed adjacent a top end of the housing, and where the bearing wall portion of the valve member is formed adjacent the top end thereof.
In accordance with a preferred embodiment of the invention, the at least one dampening member is fitted at either or both a bottom wall portion of the housing constituting the seating portion, and a bottom wall portion of the valve member housing, constituting the bearing portion.
Preferably the at least one dampening member is a resilient member axially extending from a surface of either one or both of the facing seating wall portion and the bearing wall portion.
By one specific design, the at least one resilient member extends from a bottom seating wall portion of the housing and has a valve-engaging portion upwardly projecting from a seating surface, adapted for engagement with the corresponding bottom, bearing wall portion of the valve member.
By another specific design, the at least one resilient member extends from a bearing wall portion of the valve member and has a housing-engaging portion downwardly projecting from a bearing surface thereof for engagement with a corresponding seating wall portion of the housing.
In accordance with a preferred application of the invention, the at least one resilient member is integrally formed with either or both the bottom wall portion of the housing and the bottom wall portion of the valve member.
Still preferably the at least one resilient member is an arm attached at one end thereof to the respective wall portion, and is formed at an opposed end thereof with an axial projection for engagement with the other respective wall portion.
In order to maintain the float member axially aligned within the housing, it is preferred that at least two dampening members are provided, said dampening members being symmetrically distributed about either or both of the seating wall portion of the housing and the bearing portion of the valve member.
By one specific application of the invention, the base member is integral with the housing. By a different application the base member is attached to the housing and may thus be an add-on devise, for attaching to standard valves.